Method for preparing a radical-polymerizable organopolysiloxane, a radiation-curable organopolysiloxane composition, and a release sheet

Abstract

Provided is a method for preparing a (meth)acryloyl group-containing organopolysiloxane having a step of transesterification between the components (a1) and (a2) in the presence of the components (a3) and (a4) to obtain the (meth)acryloyl group-containing organopolysiloxane, wherein component (a1) is an organopolysiloxane represented by the average composition formula (1) which has a hydroxy group-containing group, component (a2) is a (meth)acrylic acid ester represented by the general formula (2), component (a3) is a zirconium metal complex in an amount such that a molar ratio of component (a3) to the hydroxy group of component (a1) is 0.001 to 0.1, and component (a4) is a hydroxy group-containing amine represented by HON(R 4 ) 2 in an amount such that a molar ratio of component (a4) to component (a3) is 0.10 to 1.5, wherein R 4 is, independently of each other, a linear or branched aliphatic hydrocarbon group having 1 to 6 carbon atoms.

The invention claimed is: 
     
       1. A method for preparing a (meth)acryloyl group-containing organopolysiloxane, comprising a step of transesterification between the following components (a1) and (a2) in the presence of the following components (a3) and (a4) to obtain the (meth)acryloyl group-containing organopolysiloxane, (a1) an organopolysiloxane represented by the following average composition formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1  is, independently of each other, a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, or a monovalent hydrocarbon or (poly)oxyalkylene alkyl group which has a hydroxy group at a terminal, hereinafter referred to as a hydroxy group-containing group, wherein at least one of R 1  is the hydroxy group-containing group, a is a positive number of 2 or more, b is an integral number of 0 or more, c is an integral number of 0 or more, and d is an integral number of 0 or more, and 2<=a+b+c+d<=1,000,
 (a2) a (meth)acrylic acid ester represented by the following general formula (2): 
 
       
         
           
           
               
               
           
         
       
       wherein R 2  is a hydrogen atom or a methyl group and R 3  is a linear or branched hydrocarbon group having 1 to 6 carbon atoms, 
       in an amount such that a molar ratio of component (a2) to the hydroxy group of component (a1) is 1 to 10,
 (a3) a zirconium metal complex in an amount such that a molar ratio of component (a3) to the hydroxy group of component (a1) is 0.001 to 0.1, and 
 (a4) a hydroxy group-containing amine represented by HON(R 4 ) 2  in an amount such that a molar ratio of component (a4) to component (a3) is 0.10 to 1.5, wherein R 4  is, independently of each other, a linear or branched aliphatic hydrocarbon group having 1 to 6 carbon atoms; and 
 wherein (a5) a radical polymerization inhibitor is further present in the step of the transesterification in an amount of 0.001 to 1 part by mass, relative to total 100 parts by mass of components (a1) and (a2). 
 
     
     
       2. The method according to  claim 1 , wherein (a6) an organic solvent is further present in the step of the transesterification in an amount of 1 to 200 parts by mass, relative to total 100 parts by mass of components (a1) through (a4) or, if component (a5) being present, relative to total 100 parts by mass of components (a1) through (a5). 
     
     
       3. The method according to  claim 1 , wherein the zirconium metal complex (a3) is represented by the following general formula (3):
   Zr(L 1 ) e (L 2 ) f   (3)
 
 wherein L 1  is a ligand selected from a β-dicarbonylate anion and an enolate anion of a β-dicarbonyl-containing compound, L 2  is an anionic ligand different from L 1 , e is an integer of 2 to 4, and f=4-e. 
 
     
     
       4. The method according to  claim 1 , wherein the radical polymerization inhibitor (a5) is a hindered phenolic compound. 
     
     
       5. The method according to  claim 1 , wherein the number of the hydroxy group-bonding silicon atoms in the organopolysiloxane (a1) is 1 to 50%, based on the total number of the silicon atoms in the organopolysiloxane (a1). 
     
     
       6. The method according to  claim 1 , wherein the (meth)acryloyl group-containing organopolysiloxane is represented by the following average composition formula (7): 
       
         
           
           
               
               
           
         
         wherein R 5  is, independently of each other, a substituted or unsubstituted, monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group, the afore-defined hydroxy group-containing group, or a monovalent hydrocarbon or (poly)oxyalkylene alkyl group which has a (meth)acryloyloxy group at a terminal, hereinafter referred to as a (meth)acryloyloxy group-containing group, wherein at least one of R 5  is the (meth)acryloyloxy group-containing group, j is a positive number of 2 or more, k is an integral number of 0 or more, 1 is an integral number of 0 or more, m is an integral number of 0 or more, and 2<=j+k+l+m<=1,000, and the number of the hydroxy group-bonding silicon atoms is 0 to 30%, based on the total number of silicon atoms.